P-Value Calculator
Use this calculator to compute the p-value for a given z-score, t-score, F-score, or chi-square score. Select the appropriate test type and enter your score and degrees of freedom (if required).
About P-Values
A p-value is the probability of obtaining test results at least as extreme as the results actually observed, under the assumption that the null hypothesis is correct. In hypothesis testing, smaller p-values provide stronger evidence against the null hypothesis.
Common Interpretations:
- p ≤ 0.01: Very strong evidence against the null hypothesis
- 0.01 < p ≤ 0.05: Strong evidence against the null hypothesis
- 0.05 < p ≤ 0.10: Weak evidence against the null hypothesis
- p > 0.10: Little or no evidence against the null hypothesis
When to Use Each Test:
- Z-test: When population standard deviation is known and sample size is large
- T-test: When population standard deviation is unknown and sample size is small
- F-test: For comparing variances or in ANOVA
- Chi-square test: For categorical data and goodness-of-fit tests